Sealing means for rotating shaft

ABSTRACT

The present invention pertains to novel means for minimizing fluid leakage along the rotating shaft and the stationary members in conventional machinery such as pumps, compressors, and the like. Such machinery is generally provided with a sealing box positioned circumferentially around the rotating shaft wherein some form of sealing means is positioned. The present invention provides mechanical sealing means for positioning within the sealing box or housing of such machinery and comprises U-shaped members adapted to fit on the rotating shaft in such a manner so as to provide, in combination with the packing gland plate, means for minimizing fluid leakage along the shaft and between the plate and U-shaped members. Additional members are provided in combination with the U shaped members such that the forces involved will be unbalanced and the seal effected.

Sept, 18, 1973 SEALKNG MEANS FOR ROTATING SHAFT Wiliis A. Neely, l2lLevee View Dr., New Orleans, La. 70123 [76] Inventor:

Primary Examiner-Samuel B. Rothberg Attorney-Calvin J. Laiche {57]ABSTRACT The present invention pertains to novel means for minimizingfluid leakage along the rotating shaft and the stationary members inconventional machinery such as pumps, compressors, and the like. Suchmachinery is generally provided with a sealing box positionedcircumferentially around the rotating shaft wherein some form of sealingmeans is positioned. The present invention provides mechanical sealingmeans for positioning within the sealing box or housing of suchmachinery and comprises U-shaped members adapted to fit on the rotatingshaft in such a manner so as to provide, in combination with the packinggland plate, means for minimizing fluid leakage along the shaft andbetween the plate and U-shaped members. Additional members are providedin combination with the U shaped members such that the forces involvedwill be unbalanced and the seal effected.

6 Claims, 10 Drawing Figures PATENTED SE?! 8 I373 INVENTOR. WILLIS A.NEELY 1 SEALING MEANS FOR ROTATING SHAFT BACKGROUND OF THE INVENTION Thepresent invention relates to devices, commonly referred to as mechanicalseals, employed to minimize fluid leakage in fluid prime movers providedwith a rotating shaft connected to the means acting upon the fluid,e.g., an impellar.

There are two methods commonly employed today to minimize fluid leakagealong the shaft in conventional fluid prime movers incorporating arotary shaft, for example, as in the case of a centrifugal pump orcompressor. As is well known in the art, at the location where therotating shaft exits from the stationary members of a pump orcompressor, the problem exists of effecting a seal between thestationary housing of the equipment and its rotating shaft. The oldestand most commonly employed method to effect a seal in such equipment isto use what is generally known as soft packing. Exemplary of suchmaterials are braided asbestos, cotton, flax, polymeric fibers, metalfoil, graphite, and the like. Various other materials are quite oftenadded to such materials to improve their performance, such as fillingagents, lubricants, and the like. The packing is inserted in a stuffingbox circumferentially provided around the rotating shaft. Pressure isapplied to the soft packing usually by virtue of what is known as apacking gland.

Fluid leakage along the rotating shaft is controlled by in turncontrolling the clearance between the shaft and the packing which inturn is a function of the amount of pressure applied to the packing bythe packing gland. Generally, in order to provide cooling and additionallubrication for the packing and the shaft, it is necessary to allow someleakage along the shaft. Otherwise, the packing will wear the shaft. Themultitude of problems associated with soft packings, for example, therelatively excessive amount of leakage required for lubrication andcooling of the packing, as well as the wearing of the shaft and packing,have resulted in a constant thrust in the art away from such means forsealing a rotating shaft towards such devices commonly referred to asmechanical seals.

A mechanical seal as normally defined in the art generally comprises arotating member which is affixed to the shaft and a stationary memberwhich'is affixed to the sealing box portion of the piece of equipment.These members are provided with sealing faces which are in intimatecontact with each other to provide a dynamic seal. Stationary seals areprovided between the shaft and the rotating member and also between thestationary seat and the gland and between the gland and the housing. Inmost conventional mechanical seals, the rotating portion affixed to theshaft is spring loaded to produce a force along the longitudinal axis ofthe rotating shaft to thereby force it into a sealing rela-v tionshipwith the seal positioned between such member and the stationary member.Consequently, sealing is accomplished by the combination of the springloading plus the fluid loading. It is well recognized in the art that amechanical seal will not only permit less leakage along a rotating shaftand thus minimize the attendant problems of a conventional stuffing boxusing soft packing, but additionally, will generally require lessmaintenance in the form of operator attention for adjustment andlubrication. However, the components of a mechanical seal assembly aremade in integral parts which circumferentially fit around'the rotatingshaft thereby making it necessary to disassemble the piece of equipmentin order to work on the seal.

Among the advantages and features of the present invention is that theleakage rates of a conventional mechanical seal is approached, yet thepresent seal can be readily disassembled without the necessity ofdisassembling the particular piece of equipment on which it isinstalled.

SUMMARY The present invention provides a sealing means which basicallycomprises a first U-shaped member having a semi-circular inner surfaceadapted to mate with the peripheral surface of the rotating shaft onwhich the seal is to be installed. A second U-shaped member is providedwhich also has a semi-circular inner surface adapted to mate with theperipheral surface of the shaft. The members are positioneddiametrically opposite so as to encompass the shaft. The second memberis adapted to mate with the inner surface of the adjoining surface ofthe stationary member where the rotating shaft exits from the piece ofmachinery, generally referred to as the stuffing box which is providedwith a packing gland plate. Resilient means are provided in combinationwith the U-shaped members for urging them into intimate contact with therotating shaft as well as toward each other.

The second U-shaped member is preferably provided with a raised sectionwhich is adapted to fit within the extended leg portions of the firstU-shaped member to prevent its relative rotation as well as support theleg portions. Floating spacer means is also provided which is adapted toseal off the open space defined between the extended leg portions of thesecond U-shaped member and the lateral surfaces of the first U-shapedmember and the stationary member. This produces an unbalanced fluidforce which urges the member toward the shaft. Means are also providedfor preventing rotation of the seal assembly, yet to allow the assemblyto move radially with the vibratory movement of the shaft.

Additional resilient spring means are provided for urging the U-shapedmembers toward the rotating shaft and the stationary packing glandplate. The U shaped members are preferably made of a chemically inactivematerial which should also exhibit thermal stability as well as goodbearing characteristics, being preferably an aromatic polyester.

DESCRIPTION OF THE DRAWING FIG. I in the drawing depicts a front view ofone of the U-shaped members constituting one of the basic components ofthe present seal means.

FIG. 2 represents a sectional side view of the U- shaped member shown inFIG. it taken along the line 2-2.

FIG. 3 depicts a front view of the other U-shaped member.

FIG. 4 represents a sectional side view of the U- shaped member shown inFIG. 3 taken along the line 4-4.

FIG. 5 depicts one manner of securing the spacer means employed inconjunction with the U-shaped member of FIG. 4 to the stationary housingof a piece of equipment on which the present seal has been installed(see also FIG. 9). I

FIG. 6 represents a side view of the spacer means shown in FIG. 5,viewed along the line 6-6.

FIG. 7 depicts a side view of the spring means employed in conjunctionwith the U-shaped members of FIGS. 1 and 3 for constantly urging'saidmembers toward each other when in an operable relationship.

FIG. 8 represents a top view of the spring shown in FIG. 7.

FIG. 9 depicts a partial view of the various components of the presentinvention, shown in section, as installed within the stuffing box of aconventional pump or compressor.

FIG. 10 represents a view of the arrangement shown in FIG. 9 taken alongthe line 10-10.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 in thedrawings, the present sealing means 10 comprises the first U shapedmember 11 which is provided with the inner semi-circular surface 12which is adapted to fit over and mate with the peripheral surface of therotating shaft 13 (see FIGS. 9 and 10). The member 11 provides a sealingrelationship between its inner semi-circular surface and the rotatingshaft. In such manner, the member 11 in combination with the variousother components discussed in detail hereinafter forms a seal utilizingthe same principal as a conventional mechanical seal, i.e., acombination of spring and fluid loading. The second U shaped member 14is likewise provided with the semi-circular surface 15 which is adaptedto fit around the peripheral surface of the shaft 13. The members 11 and14 which are positioned diametrically opposite each other, in effectdefine a collar which encircles the shaft 13 to thereby form the sealpreventing or minimizing fluid leakage along the shaft 13.

The second U-shaped member 14 is provided with the raised section 16which is of a width and thickness such that it will slidably fit withinthe extended leg portions 17 and 18 of the member 12. The section 16primarily serves as a support for the leg portions 17 and 18 as well asprevents relative rotation or relative motion between the U-shapedmembers 11 and 14. Of course, the section 16 can be made integral withor as a separate member suitably attached to the member 14.Additionally, the exact shape shown is not critical as long as itsfunction is realized.

The U-shaped member is adapted to fit adajacent to the gland plate 21 ofthe fluid prime mover 20 in a sealing relationship. Since the design ofthe plate 21 will vary considerably with different types of equipment,it may be necessary to machine the internal surface 22 of the plate 21or provide an adapter gland plate for use with specific equipment.

The spacer 23 (FIG. 5) is provided primarily for sealing the open end ofthe U shaped member 14 as shown in FIG. 9. This produces an unbalancedfluid force in the radial direction to urge the member toward the shaft.The spacer 23 is adapted to slidably fit between the extended legportions 24 and 25 of the member 14. The member 23 is of the same widthas the U-shaped member 14 whereby said members 11 and 14 are in anoperable position, the member 23 positioned between the member 11 andthe gland plate 21, seals the open end of the member 14. In such manneras shown in FIGS. 9 and 10, the members 11, 14 and 23 in cooperationwith the gland plate 21 forms a seal assembly around the rotating shaft13 and between it and the stationary components of the prime mover 20.

Referring to FIG. 9, the U shaped resilient spring means 26 (as shown indetail in FIGS. 7 and 8) is provided for urging the U-shaped members 11and 14 toward each other into intimate contact with the shaft 13. Theresilient spring means 27 and 28 are provided for urging the sealassembly toward the gland plate 2]. The combination of the mechanicalload imparted by the springs 26, 27 and 28 and the fluid load in theaxial direction and the combination of the mechanical load imparted bythe fluid load in the radial direction achieves, in principal, many ofthe distinct advantages due to the same reason or effect as realized ina conventional mechanical seal.

As shown in FIG. 1, 2, 3 and 4, the U shaped members l1 and 14 arepreferably initially provided with the beveled inner surfaces 30 and 31.This feature of construction is preferred since it compensates formanufacturing tolerances, that is, it compensates for the difference inthe diameter of the shaft 13 and the inner diameters of the U-shapedmembers 11 and 14, viz. that of the surfaces 12 and 15. This allowsthese members to wear rapidly in position to conform to the exact shapeof the peripheral surface of the shaft 13. This effect is realized sincethe forces across the U-shaped members are maximized under suchcircumstances. Normally, the maximum force exerted on either membet isequal to the pressure exerted by the fluid medium multiplied by thediameter of the shaft times the thickness of the member, plus the springloading. Where the U-shaped members are beveled, the unit pressure overthose surfaces is greater due to the reduced surface area of contactwhich thereby causes greater or more rapid wearing. This allows thesemembers to wear into a perfect fit with the outer peripheral surfaces ofthe shaft 13. It is important that the U-shaped members fit flush orparallel with the rotating shaft so as to suppress or prevent the buildup of hydrodynamic forces along these surfaces which are created by thespinning shaft. These forces if allowed to build up, tend to lift the Ushaped members from the shaft thus destroying the seal. In any event,the interfaces between the U-shaped members and between them andtherotating shaft must be polished to maximize sealing efficiency. Itcan be appreciated that the amount of the force applied on the U-shapedmembers is primarily a function of their thickness for a given piece ofequipment, assuming a constant fluid pressure and a constant springloading.

The shaft 13 naturally produces vibratory motion due to mechanicalimperfections which commonly occur in both the axial and radialdirections. If the seal assembly were to be rigidly attached to thestationary members, then the shaft would wear an opening in the U-shapedmembers of a diameter greater than that of the shaft. In order toeliminate this effect, the entire seal assembly is allowed to travelwith the vibratory movement of the shaft. The assembly is kept fromrotation partly by virtue of the connecting means 32 which is preferablya flexible spring steel member, one end of which is tangentiallyattached to the butt portion of the U-shaped member 14 (by suitablemeans not shown) and its other end to the equipment casing. In thearrangement depicted in FIG. 9, the member 32 will allow the U- shapedmember 11 and 14 to track with the vertical component of the radialvibrations of the shaft 13. Conversely, the connecting member 33 willpermit the horizontal movement of the seal assembly to compensate forthe horizontal component of the radial vibrations of the shaft 13. Themember 33 is connected to the member 23 by suitable means, e.g., screwsand the like, and

its other end being connected to a stationary portion of the equipment.I

The U-shaped members 11 and 14 and the member 23 are constructed ofmaterials having good bearing qualities, which are chemically inactive,and thermally stable. Polymeric'materials are preferred since they ex-.

hibit these properties, especially filled polytetraon the members whichfit betweenjthe extended leg portions of the respective U-shaped memberswhich in combination with the fluid loading serves to provide a pressureseal between these members. It can be appreciated by. one skilled in thearts that variations can be made in the design of the presentsealing-means and its adaption to various equiment without departingfrom the true scope and intent of the present invention. For example,the member 23 can be allowed to ride upon the shaft 13. Or, the member23 can be made integral .with the U-shaped member ll,. similarly as inthe case of the design of the member 14. Accordingly, thescope of myinvention is that as set forth in the appended claims.

' I claim: y

l. Sealing means for-minimizing fluid leakage between the rotatingshaftand the stationary members of a fluid prime mover, saidmeans comprising;a. a first .U shaped member having a semi-circular inner surface adaptedto mate with the peripheral surface of a rotating shaft; I b. a secondU-shaped member also havingasemicircular inner surface adapted to matewith the peripheral surface of a, rotating shaft, saidsecond U- shapedmember being adapted to, mate with the vin'nersurface of a stationarymember of a fluid prime mover'where the rotating shaft exists therefromand with said first U-shaped member in a diametrically opposedrelationship so as toencompass a rotating shaft when, said U-shapedmembers are operably installed thereon; said second U-shaped memberbeing further defined in that it is provided with a raised sectionpositioned on its portion op- .posite its open end and adjacent to saidfirst U shaped 'memben'said section being adapted to slidably fit withinthe extended leg portions of said first U shaped member so as to preventrelative rotation between said members as well as support the extendedleg portions of said first U-shaped member; c. resilient means forurging said U shaped members toward each other and a rotating shaft onwhich said members are operably installed; and

d. spacer sealing means adapted to slidably fit between the extended legportions of said second U- shaped member to seal the open end thereof aswell as support said extended leg portions.

2. The sealing means of claim 1 further characterized in that:

said U-shaped' members are further defined in that theyare-provided-with beveled surfaces over their respective semi-circularinner surfaces.

3'. The sealing means of claim 2 further characterized as comprising:

e. resilient spring means for urging said first U- shaped member towardsaid second U-shaped member.

'4.' The sealing means of claim 3 further characterized in that: saidU-shaped members are constructed of an aromatic polyester which ischemically inactive, thermally stable and exhibits good bearingproperities.

5. The sealing means of claim 4 further characterized in that:

said U-shaped members are further defined in that elongated resilientspring means are embedded in their extended leg portions to impartrigidity thereto. 6. The sealing means of claim 5 further characterizedas comprising: v

f. first anchoring means :for connecting said second U-shaped member toa stationary member of a fluidprime mover on which said sealing means isinstalled, one end of said anchoring means being tangentially connectedto the outer peripheral surface of said second U-shaped member and itsother end to the stationary member to thereby prevent the seal assemblyfrom rotating and to permit the assembly to move vertically with thevertical component of the radial vibration; and

gf'second anchoring means for connecting said choring means allow saidsealing means to move both radially and axially with the vibratorymovement of the'rotating shaft.

a: a; a a a

1. Sealing means for minimizing fluid leakage between the rotating shaftand the stationary members of a fluid prime mover, said meanscomprising: a. a first U shaped member having a semi-circular innersurface adapted to mate with the peripheral surface of a rotating shaft;b. a second U-shaped member also having a semicircular inner surfaceadapted to mate with the peripheral surface of a rotating shaft, saidsecond U-shaped member being adapted to mate with the inner surface of astationary member of a fluid prime mover where the rotating shaft existstherefrom and with said first U-shaped member in a diametrically opposedrelationship so as to encompass a rotating shaft when said Ushapedmembers are operably installed thereon; said second Ushaped member beingfurther defined in that it is provided with a raised section positionedon its portion opposite its open end and adjacent to said first U shapedmember, said section being adapted to slidably fit within the extendedleg portions of said first U shaped member so as to prevent relativerotation between said members as well as support the extended legportions of said first U-shaped member; c. resilient means for urgingsaid U shaped members toward each other and a rotating shaft on whichsaid members are operably installed; and d. spacer sealing means adaptedto slidably fit between the extended leg portions of said secondU-shaped member to seal the open end thereof as well as support saidextended leg portions.
 2. The sealing means of claim 1 furthercharacterized in that: said U-shaped members are further defined in thatthey are provided with beveled surfaces over their respectivesemi-circular inner surfaces.
 3. The sealing means of claim 2 furthercharacterized as comprising: e. resilient spring means for urging saidfirst U-shaped member toward said second U-shaped member.
 4. The sealingmeans of claim 3 further characterized in that: said U-shaped membersare constructed of an aromatic polyester which is chemically inactive,thermally stable and exhibits good bearing properities.
 5. The sealingmeans of claim 4 further characterized in that: said U-shaped membersare further defined in that elongated resilient spring means areembedded in their extended leg portions to impart rigidity thereto. 6.The sealing means of claim 5 further characterized as comprising: f.first anchoring means for connecting said second U-shaped member to astationary member of a fluid prime mover on which said sealing means isinstalled, one end of said anchoring means being tangentially connectedto the outer peripheral surface of said second U-shaped member and itsother end to the stationary member to thereby prevent the seal assemblyfrom rotating and to permit the assembly to move vertically with thevertical component of the radial vibration; and g. second anchoringmeans for connecting said spacer sealing means to a stationary member,said anchoring means extending in a plane positioned essentially 90* tothat defined by said first anchoring means to thereby permit theassembly to move horizontally with the horizontal component of theradial vibration whereby both first and second anchoring means allowsaid sealing means to move both radialLy and axially with the vibratorymovement of the rotating shaft.